Blast furnace iron production with integrated power generation

ABSTRACT

An integrated system for blast furnace iron making and power production based upon higher levels of oxygen enrichment in the blast gas is disclosed. The integrated system leads to; 1) enhanced productivity in the blast furnace, 2) more efficient power production, and 3) the potential to more economically capture and sequester carbon dioxide. Oxygen enhances the ability of coal to function as a source of iron reductant and to be gasified within the blast furnace thereby generating an improved fuel-containing top gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of application Ser. No. 12/329,010, filed on Dec. 5, 2008; the disclosure of which is hereby incorporated by reference. Application Ser. No. 12/329,010 claims the benefit of Provisional Application No. 60/992,754, filed Dec. 6, 2007, and No. 61/086,237, filed on Aug. 5, 2008. The disclosure of these provisional applications is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This particular invention relates to enriching air supplied to a hydrocarbon-injected iron-making blast furnace and using the flue or top gas from the furnace to generate power. By “hydrocarbon” it is meant a fuel or reducing agent comprising oil, natural gas, petroleum coke, coal, among other materials and mixtures thereof.

Methods for combining iron production and power generation are described in “Oxygen blast furnace and combined cycle (OBF-CC)—an efficient iron-making and power generation process”, Y. Jianwei et al., Energy 28 (2003) 825-835.

Air Separation Units (ASUs) and methods for making oxygen therein are described in U.S. Pat. No. 5,268,019; hereby incorporated by reference. Methods for combining iron making process with an ASU are described in U.S. Pat. No. 5,582,029 and WO 9728284-A1.

Methods for combining an ASU and power generation are described in “Developments in iron making and opportunities for power generation”, 1999 Gasification Technologies Conference, San Francisco, Calif., Oct. 17-20, 1999. This publication also describes using coal in iron production in order to reduce the amount of coke that is required.

U.S. Pat. No. 6,216,441 B1 discloses removal of inert gases from flue or top gas prior to combustion of it in a gas turbine or combined cycle power plant.

The disclosure of the previously identified patents and patent applications is hereby incorporated by reference.

There is a need in this art for an integrated system that combines coal gasification and oxygen enriched iron production from a blast furnace with power generation, and, if desired, carbon dioxide removal and sequestration.

BRIEF SUMMARY OF THE INVENTION

The instant invention solves problems associated with combining conventional iron production methods with higher efficiency combined cycle power production from combustion of the top gas by providing an integrated system based upon maximizing the caloric or heat value in the top gas, and simultaneously increasing the productivity of the furnace hot metal production. The integrated system includes operating the blast furnace in a manner wherein at least one of the following is achieved: a) pulverized coal injection (PCI) rate is maximized and combined with b) “super-enrichment” of air supplied to the blast furnace with oxygen (e.g., via an ASU, a membrane, among other suitable means for generating oxygen) wherein “super-enrichment” of the blast air with oxygen means enriching the blast to an oxygen concentration above about 32% and up to about 70% by molar volume (e.g., at least 40% to about 60% by molar volume), c) steam is added to the oxygen enriched blast to enhance production of hydrogen as well as control temperature in the lower part of the blast furnace (e.g., steam can be extracted from the combined cycle (CC) steam turbine), and d) coke consumption rate is minimized to the extent that it is sufficient to provide support and gas permeability during the ore reduction process. The super enriched air (and if desired steam) enhance the coal gasification in the furnace to produce reducing gases of CO and H2, thus replacing more expensive metallurgical coke. The super-enriched air also permits at least one of: a) increasing in the amount of coal used in the furnace, b) more complete gasification, c) improving the iron-making productivity of the given furnace, and d) generating a higher calorific value, or fuel-containing top gas that can be matched to a downstream process for maximum efficiency of downstream process operation (e.g., in some cases, with little or no supplemental fuel).

Maximizing the PCI injection leverages the efficient desulfurizing and energy converting characteristics of the blast furnace to produce in combination with downstream top gas treatment and conversion processes and equipment at least one of power, syngas, steam, among other benefits. Operation of a blast furnace with PCI injection can be combined with super-enriched air that can obviate the need for conventional hot blast stoves.

One aspect of the invention relates to iron production and coal gasification that is integrated with combined cycle power generation.

Another aspect of the invention relates to iron production and coal gasification where oxygen injected into the blast furnace is generated from an ASU that is also integrated into the combined cycle gas turbine to provide nitrogen for cooling and mass enhancing, and any excess compressed air from the compressor supplying combustion air to the gas turbine is supplied to the ASU.

Another aspect of the invention relates to iron production and coal gasification that is integrated with combined cycle power generation and carbon dioxide capture for possible sequestration both of which are enabled and enhanced by the reduced concentration of N2 in the topgas resulting from the use of super enriched oxygen blast. Capturing or removing carbon dioxide can increase the fuel value of the topgas, reduce or eliminate the amount of carbon dioxide supplied to the furnace in an optional recycle loop, among other benefits.

A further aspect of the invention relates to iron production and coal gasification that is integrated with combined cycle power generation and carbon dioxide capture, with the additional inclusion of a shift reactor prior, to the carbon dioxide removal and capture step, so as to enable greater proportions of carbon dioxide to be removed and captured.

Another aspect of the invention relates to iron production and coal gasification that is integrated with combined cycle power generation and CO2 capture, taking advantage of the steam generated from the heat contained in the exhaust from the gas turbine or the nitrogen from the ASU to drive the shift reactor or a CO2 removal (e.g., sequestration) process.

A further aspect of the invention relates to iron production and coal gasification that is integrated with top gas cleanup and/or CO2 removal for production of syngas.

One aspect of the invention relates to a method for producing iron comprising:

introducing iron ore, coke and coal into a blast furnace, whereby the coal is gasified by introducing super-enriched air into a blast furnace, and recovering from the blast furnace a top gas, using the top gas to generate power; and, recovering hot metal from the blast furnace.

Another aspect of the invention relates to a method for generating power comprising:

providing a top gas, or portion of top gas, from a blast furnace comprising carbon monoxide, carbon dioxide, hydrogen, nitrogen in concentration such that it has a calorific value matched, without supplemental fuel, to fall within the required fuel value operating range of a downstream gas turbine,

introducing the gas into a gas turbine under conditions sufficient to generate power, and;

introducing the exhaust from the gas turbine into a heat recovery steam generator under conditions sufficient to generate power.

A further aspect of the invention relates to a method for gasifying coal and producing iron comprising:

-   -   introducing coal into an ironmaking blast furnace, and;         introducing air enriched in oxygen into the blast furnace,     -   wherein the conditions within the blast furnace are sufficient         to convert at least a portion of the coal into a gas comprising         carbon monoxide, carbon dioxide and hydrogen;     -   removing a portion of the gas from the furnace,     -   removing at least a portion of the carbon dioxide from the gas,         supplying the gas to at least one of a combined cycle power         generation system, a shift reactor and the ironmaking blast         furnace; and,     -   recovering iron from the ironmaking blast furnace.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic illustration of one aspect of the invention that employs coal gasification and combined cycle power generation in connection with Blast Furnace iron production.

FIG. 2 is a schematic illustration of another aspect of the invention that employs coal gasification and combined cycle power generation and carbon dioxide capture and removal (for possible sequestration) in conjunction with Blast Furnace iron production.

FIG. 3 is a schematic illustration of yet another aspect of the invention that employs coal gasification and combined cycle power generation together with carbon dioxide capture and removal (for possible sequestration) that is enhanced by the inclusion of a shift reactor prior to the carbon dioxide capture and removal step.

FIG. 4 is a schematic illustration of another aspect of the invention that employs nitrogen from an ASU to assist in powering a gas turbine and oxygen from the ASU to assist in combusting at least a portion of the top gas in a HRSG.

FIG. 5 is a schematic illustration of further aspect of the invention that employs a gas holder to dampen flow and pressure variations in the top gas, and where at least a portion of the treated top gas is directed around the gas turbine to the HRSG.

FIG. 6 is a schematic illustration of one aspect of the invention that employs stoves to provide a heated blast wherein a portion of the blast air is provided by air extracted from the compressor feeding combustion air to the gas turbine.

FIG. 7 is a schematic illustration of another aspect of the invention illustrated in FIG. 1 except that FIG. 7 employs hot blast stoves and an air blower for supplying heated oxygen enriched air to the blast furnace.

The apparatus, components, systems and methods illustrated in these Figures can be employed individually or in combination to obtain additional aspects of the invention that are not illustrated by the Figures.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention relates to apparatus, processes and compositions for providing an integrated system that utilizes oxygen enrichment of air supplied to a blast furnace (e.g., via an ASU) to efficiently combine coal gasification and blast furnace iron production. The integrated system gasifies coal in situ within the iron blast furnace and produces a flue or furnace top-gas having improved utility for power generation and, if desired, from which carbon dioxide can be removed and sequestered.

Additional oxygen beyond that which is normally supplied to the air blast is either directly injected or combined with the blast air being supplied to the blast furnace to enhance the effectiveness of the blast furnace to accept a relatively large amount of injected hydrocarbons or fossil fuels, for example coal from a pulverized coal injection system (PCI), and/or to enable more pulverized coal to be injected. Such a PCI system reduces the amount of coke that is required for iron production in a blast furnace. In addition, supplying oxygen enriched air to the blast furnace can produce: 1) a flue or top-gas that has reduced nitrogen content and increased fuel or calorific value, 2) a top gas that has enhanced value for power generation, 3) a top gas that is compatible with gas turbine power generators, 4) a top gas obtained by in situ coal gasification within the blast furnace, among other benefits. In a marked improvement over conventional methods, the integrated system of the instant invention obtains a top gas that can have an increased concentration of hydrogen and carbon monoxide and, in some cases, a reduced amount of nitrogen.

In one aspect of the invention, coal can be combined or separately co-injected with other hydrocarbons.

The instant invention permits controlling and selecting a desired economic base of operation that is achieved by valuing the benefit and cost of the following variables: coke, coal, iron, oxygen, power and stove utilization (i.e., hot blast). For a given cost of coke, oxygen and coal, the optimum value of iron and power can be selected. Generally, increasing the amount of coal introduced into the blast furnace will allow to increase the amount of oxygen used, but reduce the amount of coke employed and in turn reduce the cost of iron production. Similarly, increasing the amount of coal will also allow to increase the amount of oxygen used and allow to lower the hot blast temperature (e.g., the amount of heat supplied from the stoves can be reduced), and increase the amount of power that can be generated. Depending upon the relative economic value of the foregoing variables, it may be possible to eliminate the hot blast (stoves) and hence use the energy previously consumed by the stoves to generate power, or for operating a water shift reactor, carbon dioxide removal, among other systems.

If desired, the oxygen used for enriching air that is introduced into a blast furnace can be supplied from any suitable gas separation system such as cryogenic distillation including an ASU, a membrane (e.g., an ion transport membrane), pressure vacuum swing adsorption (PVSA), among other systems suitable for generating an oxygen containing stream that can be used for enriching air. As a result of employing higher levels of oxygen enrichment or super enrichment, the oxygen enriched blast may be supplied directly to a blast furnace at ambient temperature conditions thereby obviating, if desired, the need for hot blast stoves (e.g., stoves that use top gas to heat air prior to introduction to the blast furnace), and permitting the energy typically consumed by the hot blast stoves to become additionally available for generating power. Information relating to introducing oxygen enriched air into a PCI blast furnace can also be found in A. Poos and N. Pongis, “Potentials and problems of high coal injection rates”, 1990 Ironmaking Conference Proceedings.

While any suitable ASU can be employed, an example of suitable ASUs are those supplied commercially by Air Products And Chemicals, Inc., Allentown, Pa. Suitable ASUs are also described in U.S. Pat. No. 5,268,019; hereby incorporated by reference. A gas separation system such as an ASU can produce an oxygen containing stream which when combined with air in blast furnace air can have an oxygen concentration of from about 40 to less than about 100% by volume. An oxygen containing stream from the ASU can be blended or combined with air (either heated or ambient) to provide a predetermined concentration of oxygen to the blast furnace (e.g., from about 35 to up to nearly pure oxygen, but more typically between about 40 to about 70% oxygen). An oxygen containing stream from the ASU can also be supplied to the duct burner of the HRSG to enhance combustion of relatively low-calorific topgas (e.g. for improving steam generation). If desired, nitrogen produced from the ASU can be supplied to a gas turbine (e.g., as described below a gas turbine used to generate power from the blast furnace top gas), in order to increase the effectiveness of the turbine and to maintain proper combustion temperature and mass flow volume. Similarly, excess compressed air generated by the feed compressor to the gas turbine can be extracted and supplied to the ASU in order to increase the effectiveness of the ASU, or the compressed air can be used to supplement or supplant air that is supplied to the blast furnace stoves (e.g., air that is introduced into the stoves by an air blower). Power generated from a generator driven by a gas or steam turbine can in turn be supplied to the ASU

If desired, the oxygen enriched air being supplied to a fossil fuel injected (e.g., PCI), blast furnace can be modified by introducing steam (e.g., steam generated in connection with power generation described below). Steam can be combined with the oxygen enriched air or supplied separately to the PCI blast furnace. Introducing steam to the blast furnace can have two beneficial and simultaneous effects. First, it can be used to moderate the flame temperature in the lower part of the blast furnace which might otherwise be too high due to oxygen enrichment. Second, the reaction of steam with the injected pulverized coal and hot coke present in the lower part of the blast furnace will increase the amount of hydrogen (and in some cases carbon monoxide) in the gas produced within the blast furnace. This additional hydrogen gas specie can then participate in driving iron reduction while also enhancing the top gas calorific content which, in turn, makes the top gas more useful for power generation (e.g., in combined cycle power generation). While any suitable concentration of steam can be employed, typically the amount of steam ranges from about 10 up to about 250 grams/Nm3 of blast volume (e.g., from about 50 to about 150 grams/Nm3 and in some cases from about 20 to about 60 grams/Nm3 of blast volume).

In one aspect of the invention, the oxygen enriched air further comprises steam, at least one member selected from the group consisting of carbon monoxide, carbon dioxide and hydrogen. Oxygen can be obtained from an ASU and carbon monoxide, carbon dioxide and hydrogen obtained by recycling a portion of the top gas. As a result, a top gas that is substantially free of nitrogen can be produced. By “substantially free” it is meant that the top gas comprises less than about ten (10) volume percent nitrogen (e.g., less than about 8 volume percent).

The instant invention can permit lowering the temperature of the blast (e.g., comprising oxygen enriched air), that is introduced into the furnace from a typical hot blast temperature of about 1100 to 1250 C, to 850 C and in some cases to about 600 C. Generally, a lower blast temperature will depend upon and employ an increased amount of oxygen. By “blast temperature” it is meant the equilibrated temperature of the oxygen enriched air stream as it enters the blast furnace at the tuyeres. If desired, a blast temperature can be prepared by mixing ambient temperature oxygen into ambient temperature air ahead of the stoves and then heating the entire mixture to the desired and equilibrated blast temperature. Alternatively, the ambient temperature air can be heated alone in the stoves to a temperature above that of the desired blast temperature, and the relatively cold ambient temperature oxygen can be added into the heated air blast downstream of the stoves to produce the mixture of oxygen enriched air blast at the desired concentration of oxygen and at the desired hot blast temperature. The temperature of components used to prepare the blast can vary and can be combined in any suitable manner to produce the hot air blast at the desired temperature and oxygen concentration. While the oxygen and air are normally combined prior to being introduced into the furnace, if desired, they can be introduced separately and an ‘equivalent’ hot blast temperature can be obtained which corresponds to the temperature of the oxygen enriched blast if the two streams had been mixed and equilibrated in temperature together.

The temperature of the oxygen enriched air blast, PCI rate, coke rate, hot metal flow or release rate, and oxygen/steam concentration can be controlled in order to obtain a top gas having a desired calorific value. Typically the calorific value of the top gas will range from about 110 to about 170 btu/scf (e.g., the calorific value can vary depending upon the concentration of oxygen used in the air blast such that the top gas calorific value may vary from about 110 to about 130 btu/scf when the oxygen enriched air comprises about 40 vol. % oxygen to about 135 to about 170 btu/scf when the enriched air comprises about 60 vol % oxygen).

One aspect of the invention relates to removing carbon dioxide from the top gas. Any suitable method can be employed for removing carbon dioxide from the top gas. In one aspect of the invention, the carbon dioxide is removed by using stripping absorbent beds such those as described in U.S. Pat. No. 5,582,029; hereby incorporated by reference. In another aspect of the invention, carbon dioxide is removed by being exposed to a solution comprising MEA (e.g., a solution comprising about 20% MEA), among other suitable solutions. By removing carbon dioxide from the top gas, the instant invention permits controlling the amount of carbon dioxide released into the environment as well as provides a top gas having improved fuel value for subsequent power generation, among other uses.

If desired, prior to removing the carbon dioxide from the top gas, carbon monoxide in the top gas can be converted to carbon dioxide by a shift reactor. That is, a reactor wherein carbon monoxide and water are converted into carbon dioxide and hydrogen (e.g., as described in U.S. Patent Application Publication No. US20060188435A1 and U.S. Pat. No. 4,725,381A; both hereby incorporated by reference). The carbon dioxide can be removed in the manner described above and the remaining hydrogen employed for generating power, purifying petroleum products, supplied to a fuel cell for generating power, among other uses. Alternatively, the top gas can be converted into ammonia, methanol, among other products, in addition to or instead of being used for generating power.

In another aspect of the invention, the top gas can be used for generating power. While the top gas can be used in any suitable power generation system, an example of a suitable combined cycle power generation system is disclosed in U.S. Pat. No. 6,216,441 B1 (hereby incorporated by reference). The top gas can be combusted in a gas turbine and/or a heat recovery steam generator in order to generate power. If desired, carbon dioxide can be removed (and, if desired, sequestered, used in subsequent chemical processes, among other uses), from the top gas prior to introducing the top gas to the power generation system. Capturing CO2 prior to combustion can be more desirable than capturing CO2 from the exhaust gas of the HRSG where the CO2 content of the gas would be more dilute and the exhaust gas would contain O2.

In one aspect of the invention, exhaust emitted from the power generation system is substantially free of carbon dioxide. By “substantially free” of carbon dioxide it is meant that the exhaust contains less than about five vol. % carbon dioxide. The exhaust can be substantially free of carbon dioxide and carbon monoxide by employing the previously described water shift reactor to convert carbon monoxide and water into carbon dioxide and hydrogen prior to the CO2 removal process (e.g., a water shift process is performed prior to CO2 removal such as illustrated in FIG. 3).

In a further aspect of the invention, a series of gas and steam turbines can be employed for generating power. The number of turbines, calorific value of the top gas, ratios/rates of materials supplied to the turbines, and supplemental fuel gas can be controlled in order to maximize the economic value of the inventive method and system (e.g., in one aspect to maximize the amount of power generated).

In one aspect of the invention, the power generation system can be operated without supplying supplemental quantities of fuel gas from an external source (sometimes referred to as “trim fuel”). Typically, in this aspect of the invention the gas turbine and the HRSG will be operated with less than about ten percent (10%) of the calorific value of the gas being obtained from supplemental fuels or externally generated or supplied fuel gas (e.g., natural gas, carbon monoxide, among other fuels). While a desired aspect of the invention is to reduce or eliminate usage of supplemental fuels, all aspects of the instant invention do not preclude usage of supplemental fuels.

Certain aspects of the invention are illustrated by the drawings. Referring now to the drawings, FIG. 1 illustrates one aspect of the invention comprising an integrated iron production and coal gasification system wherein the amount of coke 1 introduced into a blast furnace (BF) 2 is reduced due to implementation of a pulverized coal injection (PCI) system 3. Oxygen enriched air is supplied by combining air with oxygen generated by an air separation unit (ASU) 4. The flue or top gas 5 emitted from the blast furnace 2 is collected and cleaned in a gas cleaning system 6 (e.g., by cyclone or wet venturi system). Following the cyclone and wet scrubbing system, any additional particulates can be removed from the top gas by additionally passing it through an electrostatic precipitator 7 making (and ensuring that) it is adequately clean for use in compressors and gas turbines. The top gas is then compressed in a flue gas compressor (FGC) 8 and introduced into a gas turbine (GT) 9 thereby generating power. The combusted top gas/air mixture, released from the gas turbine 9, is then introduced into a heat recovery steam generator (HRSG) 10 to make steam through thermal transfer. The steam is passed through a steam turbine (ST) 11 to generated power.

In the aspect of the invention illustrated in FIG. 1 (and other aspects of the invention), the amount of hot metal 12 produced can be increased. Typically the usage of coke is less than about 300 kg per metric ton of hot metal and the coal rate is at least about 200 kg per metric ton of hot metal (or about 0.40 kg of carbon per kg of iron produced). In some cases, the fuel (e.g., also known as reducing agent) to iron ratio is greater than about 0.45 kg of carbon per kg of iron produced.

FIG. 2 illustrates another aspect of the invention wherein the system of FIG. 1 is modified to include a system 13 for removing carbon dioxide prior to introducing the top gas to the gas turbine 9. While any suitable system can be used for removing carbon dioxide, one example of a suitable system comprises the use of a physical solvent such as commercially available SELEXOL® system (supplied by UOP LLC, Des Plaines, Ill.), to capture and remove the carbon dioxide from the stream of gas. Compressed top gas from the FGC 8 containing carbon dioxide is introduced to the carbon dioxide removal system 13. The removal system 13 receives low pressure (LP) steam and produces carbon dioxide and water (if desired, the LP steam can be supplied by the HRSG 10). The carbon dioxide can be recovered as a product, sequestered, and or submitted for other uses known for carbon dioxide (such as for use in enhanced oil recovery (EOR)). In one aspect of the invention, nitrogen as a diluent (e.g., from the ASU 4) can be introduced at any suitable location such as after carbon dioxide removal, into the gas turbine 9 for flame cooling in the gas turbine and mass flow enhancement.

FIG. 3 illustrates another aspect of the invention wherein the system of FIG. 2 is modified to include a shift reactor 14. Typically, the reactor 14 is located in the system prior to carbon dioxide removal 13. The reactor 14 combines steam (e.g., from the HRSG 10), with carbon monoxide in the top gas to produce carbon dioxide and hydrogen. By including a shift reactor 14 in the process flow ahead of the carbon dioxide removal step 13, more of the carbon-containing gas species are readied for removal and capture prior to final exhausting of the combustion products from the entire system. By this means, a greater proportion of the carbon dioxide can be removed in the subsequent system 13 (e.g., Selexol® process). Furthermore, the increased concentration of hydrogen improves the fuel value of the remaining gas which can then be used for power generation, among other uses. If desired, a stream comprising hydrogen and nitrogen can be obtained from the carbon dioxide removal system 13 (e.g., for uses other than power generation).

FIG. 4 illustrates another aspect of the invention wherein the system of FIG. 2 integrates the HRSG 10, and the oxygen and nitrogen produced by the ASU 4 with other components of the system. Nitrogen produced by the ASU 4 can be supplied to the PCI system 3 in order to transport/convey the pulverized coal, remove water, among other utilities. Nitrogen produced by the ASU 4 can also be supplied to the gas turbine 9 in order to enhance the effectiveness of the turbine. In addition, the effectiveness of the ASU can be increased by receiving excess compressed gas, if any, extracted from the compressor feeding combustion air to the gas turbine 9. In addition to the previously described uses, oxygen from the ASU 4 can also be supplied to the HRSG in order to enhance the effectiveness of combustion of any excess top gas (e.g., gas not directed to the gas turbine) within a duct (not shown) leading to the HRSG. Steam from the HRSG 10 can be supplied to the steam turbine 11, blast furnace 2, carbon dioxide removal system 13, shift reactor 14, among other uses. If desired, the aspects of the FIG. 3 such as the shift reactor 14 can also be incorporated into the system illustrated in FIG. 4.

FIG. 5 illustrates another aspect of the invention wherein the system of FIG. 2 employs a gas holder 17. The gas exiting the wet ESP 16 is supplied to the FGC 8 and, if desired, to the HRSG 10 and combusted therein using oxygen supplied by the ASU 4. Examples of wet ESP systems are disclosed in U.S. Pat. Nos. 7,318,857; 6,294,003; 6,110,256; 5,039,318; 5,084,072; and 4074983; hereby incorporated by reference. Steam from HRSG is supplied to the steam turbine 11 from generating power which can be used, for example, for operating the ASU 4. If desired, the aspects of FIGS. 3 and 4 such as the shift reactor 14 can also be incorporated into the system illustrated in FIG. 5.

FIG. 6 illustrates another aspect of the invention wherein the system of FIG. 2 employs stoves 18 for generating a hot blast that is provided to the blast furnace 12. At least a portion of the blast air can be provided by compressed air extracted from the combustion air compressor for the gas turbine 9. An advantage may derive from this system because the compressed air will already be somewhat heated by the act of compression, and use of this compressed air in feed to the stoves may reduce both the thermal energy input needs of the stoves as well as some of the power needs of the blowers used to create the blast. The gas exiting the gas turbine 9 can be controlled in order to optimize the value of supplying the gas to the stove 18 or the HRSG 10, or both.

FIG. 7 illustrates an aspect of the invention illustrated in FIG. 1 except that FIG. 7 employs hot blast stoves, an air blower and a gas holder. Referring now to FIG. 7, this process employs an enhanced calorific value topgas that is first directed through a cyclonic or reversing-flow dust catcher for cleaning and drop-out of large particulates. Next the gas is cleaned through a Bischoff venturi (annular gap) wet scrubber to remove more of the dust. Following the wet scrubber, the gas passes through a demister to remove entrained or condensing water from the topgas. The three components of ductcatcher, venturi scrubber, and demister are typically existing components on all blast furnaces.

In the event, the blast furnace is designed and operated with high top pressure, there may be an existing topgas pressure recovery let-down turbine (not shown in FIG. 7) following the existing gas cleaning system. The existence (or lack-there-of) of any topgas recovery turbine does not affect the overall scheme of this invention. Following the existing gas cleaning system and the top gas pressure recovery turbine (if it exists), the gas is directed through a wet electrostatic precipitator to make it suitable for fuel gas compression. The gas is next directed through a fuel gas compressor to boost its pressure to that required for the inlet of the Gas Turbine. Since the fuel gas is at a compressed state to enter the gas turbine, and it will already be compressed at this point, there is the option of advantageously performing a CO2 removal step at this stage. The now-enhanced calorific fuel gas (enhanced from either the operating parameters implemented at the Blast Furnace and/or as a consequence of CO2 removal from the fuel gas) is introduced and combusted in a Gas Turbine to produce shaft power to produce power and to drive a generator and the compressor which provides the combustion air for the gas turbine.

The hot exhaust from the gas turbine is directed to a Heat Recovery Steam Generator (HRSG) to make steam and to produce more power via steam turbine (“Combined Cycle”).

To maximize the use of the topgas and accommodate with flow variations within the blast furnace, a gas collection and pressure management system is installed. This includes a gasholder, specialty controls, and trim gas mixing system (as required).

The technical effects of the system illustrated in FIG. 7 include:

-   -   Increased coal and oxygen injection.     -   Diminished use of coke, giving large operating (coke cost)         savings.     -   Lowered hot blast temperature, enabling a greater portion of the         top gas to go to power production (meaning that less CO₂ is         emitted from stove heating and hot blast creation).     -   An enhanced (elevated) calorific-value top gas enabling the         topgas to be burned directly in a gas turbine as the first step         in the more efficient Combined Cycle power production.     -   Oxygen enrichment up to the level of 60% oxygen in the hot blast         (overall).     -   Incorporation of gas collection, cleaning, and management         systems.

The following Examples are provided to illustrate certain aspects of the invention and shall not limit the scope of the claims appended hereto.

Example A

Example A illustrates the affect of increased coal injection and increased oxygen concentration in the blast on blast furnace performance. A blast furnace of 2,855 m³ working volume is normally operated according to the parameters of Table 1 column (a) (shown below). These parameters are used for purposes of comparison to illustrate certain desirable aspects of the instant invention by using a mass and energy balance computer model for the Blast Furnace. The computer model used in the instant Example is a conventional two-stage mass and heat balance model as described and employing the equations disclosed in “Principals of Blast Furnace Ironmaking” by Anil K. Biswas (1981 Cootha Publishing House, Brisbane, Australia). The computer model is used to illustrate the blast furnace operation at increasing amounts of pulverized coal injection and increased oxygen concentration in the hot air blast.

The composition of charge materials is held constant as well as the quantity (18 g/Nm3) of moisture in the hot blast. Next, coal and oxygen are introduced into the blast furnace operation according to the values shown in cases (b) through (i) of Table 1. These parameters include increasing the coal injection rate and the blast oxygen content. Depending on the hot blast temperature, the blast furnace operation could be balanced at different coke rates for each of the increase coal injection rates. The affect of these parameters on the production rate of both topgas and hot metal from the blast furnace are shown in Table 1.

This Example also illustrates the affect of using a portion of the topgas as fuel to fire the stoves. The portion employed as fuel is dependent upon amount of hot blast to be used in the process and its temperature. Subtracting the portion of topgas used for stove firing from the total topgas produced gives the remaining amount of topgas available to be used for other purposes such as downstream power production. Multiplying the quantity of remaining topgas available for other uses by its calorific content gives the amount of thermal energy available for conversion to electricity.

For an increase of pulverized coal injection (up to the operational maximum), it is possible to balance the operation across a spectrum of new operating parameters. Columns (b) and (c) of Table 1 show two different operating cases wherein the rate of pulverized coal injection was increased from the base case of 150 Kg/T of column (a) to 200 Kg/T.

In the case of operation shown in (b), the coal injection is increased to 200 Kg/T while the hot blast temperature is maintained at a constant 1250° C. For this case, the oxygen concentration in the blast is increased from 26.6% oxygen in the base case (a) to 30.1% oxygen in case (b). As shown in Table 1, the results of this balanced operation are:

-   -   i.) a reduction in the required volume of hot blast;     -   ii.) a corresponding reduction in the amount of topgas needed to         be taken to heat the stoves;     -   iii.) an increase in the calorific value of the topgas;     -   iv.) an increase in the corresponding amount of both the topgas         and thermal energy which can be made available for other         downstream purposes such as electric power production by         directing this topgas to Rankine or combined cycle power         production as may be appropriate;     -   v.) a reduction in the coke rate required by the operation; and     -   vi.) a production increase.

In the case of the operation shown in (c), coal injection is increased to the same level as in case (b), i.e., 200 Kg/T, but the oxygen concentration in the air blast is further increased to 34.8% in balanced operation. The results of this operation are:

-   -   i.) a reduction in the required hot blast temperature from         1250° C. to 800° C.;     -   ii.) a slightly further reduction in the required volume of hot         blast;     -   iii.) an even further reduction in the amount of topgas needed         to be taken to heat the stoves;     -   iv.) a further increase in the calorific value of the topgas;     -   vii.) an even larger increase (over case (b)) in the         corresponding amount of both the topgas and thermal energy which         can be made available for other downstream purposes such as         electric power production by directing this topgas to Rankine or         combined cycle power production as may be appropriate;     -   v.) a coke rate increase against case (b), but still less than         (a); and     -   vi.) a production decrease against case (b), but still an         increase over case (a).

Comparing cases (b) and (c) against base operation (a) illustrates that the overall operation of the blast furnace can be improved and selectively adjusted to find an optimum in economical production depending on the costs of coke, coal, and oxygen; and the relative value of hot metal production, and the value of the topgas to downstream power production.

Referring now to cases (d), (e) and (f), these cases illustrate increasing the coal injection rate to 240 Kg/T. Each of these three cases are achieved with increased oxygen percentages in the blast. However, depending on the percentage of oxygen added to the blast, the hot blast temperature employed for balanced operation changes for the given coal injection rate. As before, the highest amount of topgas and topgas energy for power production occurs when the percentage of oxygen in the air blast is maximized, the hot blast temperature is lowered, and production of iron is restrained at the fixed coal injection rate.

Among the three cases (d), (e) and (f), the lowest coke rate occurs at the highest hot blast temperature case (d). As the coke introduction rate in the blast furnace reduces, effective operation of the blast furnace may become difficult due to complications associated with even distribution of the coke. Accordingly, these examples illustrate operations employing at least 262 Kg (or more) of coke per Ton of hot metal (i.e., 262 Kg of coke per Ton of hot metal has been demonstrated to be effective).

Coal Injection is increased further to 280 Kg/T shown in cases (g) and (h). In these two cases, the hot blast temperature is reduced in order to maintain balanced operation while increasing oxygen enrichment of the air blast in order to maintain at least 262 Kg/T of coke in the charge mix. The results of cases (g) and (h) are:

i.) even greater production of hot metal, and

ii.) topgas with increased thermal energy for downstream power production, over all of the previous cases.

Further increase coal injection to 320 Kg/T in case (i) of Table 1 while holding hot blast temperature equivalent to the 600° C. of previous case (h) results in a coke rate requirement of only 239 Kg/T. To allow for balanced operation at a level of (320 Kg/T) of coal injection and with the level of oxygen enrichment shown, further decreases in the hot blast temperature would be appropriate to allow for more coke in the charge while maintaining a balanced operation.

At some threshold level of calorific value (e.g., a calorific value greater than 4,700 kJ/Nm3), the topgas becomes amenable for conversion into electricity at improved efficiency by burning directly in a Gas Turbine without the need for supplemental fuels. Thus, producing topgas of higher calorific value gives advantage to downstream power production from this topgas.

Operating the BF in the regime of increased oxygen content in the blast, together with increased coal injection, shows benefits of:

-   -   i.) increased topgas energy creation,     -   ii.) reduced coke requirement in the Blast Furnace,     -   iii.) reduced requirement of topgas energy for stove heating         through:         -   a. lowering of the hot blast temperature requirement, and         -   b. lowering the total flow rate of hot blast required,     -   iv.) increased production of hot metal from a given fixed asset         of a given size Blast furnace.

TABLE 1 Case Units (a) (b) (c) (d) (e) (f) (g) (h) (i) BF Inputs Injected coal Kg/T 150 200 200 240 240 240 280 280 320 rate Blast Oxygen % 26.6 30.1 34.8 35.5 38.1 40.2 42.0 44.1 48.7 content Hot Blast ° C. 1250 1250 800 1250 800 600 800 600 600 Temp. Operational Results Coke rate Kg/T 339 296 327 262 300 317 263 278 239 Req'd Hot Nm3/min 4848 4,600 4586 4,385 4374 4368 4146 4142 3897 Blast Vol. Topgas kJ/Nm3 3,579 3,929 4,291 4,235 4,574 4,722 4,881 5020 5344 Calorific Value Btu/scf 91 100 109 108 116 120 124 128 136 Topgas Quantity Produced Nm3/T 1385 1,322 1,360 1,272 1306 1322 1253 1267 1213 Req'd for Nm3/T 510 424 225 364 195 130 168 112 96 stoves Avail. for Nm3/T 875 898 1,135 908 1111 1192 1085 1155 1117 power prod. Thermal mill. 1.041 1.223 1.659 1.379 1.791 1.969 1.935 2.102 2.246 energy for MJ/hr power BF Productivity T/day 7,983 8,319 8,174 8,606 8,460 8,394 8,767 8,700 9,028

Example B

This Example illustrates modifying conventional blast furnace operation to cold (ambient temperature) blast operation. The operating parameters for a conventional blast furnace operated to achieve high rate of coal injection with high hot blast temperature and oxygen enrichment to drive it to the lowest practical amount of coke in the charge for stable operation and are shown in column (a) of Table 2 shown below (e.g., the hot blast temperature is 1250° C.; the coal injection rate is 240 Kg/T; the elevated temperature blast is enriched with oxygen to the level of 33.5%; and the coke rate is 262 Kg/T [base case (a) of Table 2 corresponds approximately to case (d) of Table 1]). The computer model described in Example A is also used in Example B.

One constraint to any modified Blast Furnace operation is satisfying the thermal requirements in the lower part of the furnace indicated as the Raceway Adiabatic Flame Temperature (RAFT). The RAFT preferably falls within a range of about 1950 to 2300° C. when the conventional operating parameters are being satisfied.

Case (b) in Table 2 shows the results from operating the conventional blast furnace of case (a), with the following modifications:

i.) increased coal injection,

ii.) increased air blast oxygen, and

iii.) blast temperature reduced to ambient (25° C.)

while satisfying the thermal conditions in the lower part of the furnace (as illustrated by a calculated RAFT of 1996° C.). In this case (b), the Blast Furnace is operated with an ambient temperature blast that is enriched to 55.5% oxygen with the same coke rate as in the base case (a) when the coal injection rate is 335 Kg/T. Case (b) illustrates operation of the blast furnace wherein:

-   -   i.) the productivity of the blast furnace is raised,     -   ii.) the calorific value of topgas is increased 5,744 kJ/Nm3         thereby making it useful in direct firing in a gas turbine of a         combined cycle power generating operation.     -   iii.) since the blast temperature is accepted at ambient, the         need to employ part of the topgas as fuel for stove heating can         be eliminated which in turn permits the entire topgas stream to         be employed for other useful purpose (such as combined cycle         power production).

The previously identified computer model is used to illustrate other modified operating schemes and arrangements for the Blast Furnace of case (a). Case (c) illustrates the affects to furnace operation if some of the topgas is subjected to a CO2 stripping operation, and the remaining CO/H2-enriched topgas stream is recycled and reinjected into the blast furnace through the tuyeres along with the oxygen-enriched ambient temperature air. In case (c), 46 Nm3/T of CO2-stripped and recycled topgas is prepared and injected through the Blast Furnace tuyeres along with the required oxygen-enriched cold blast for a balance operation. The results for this example case (c) in Table 2 show that:

-   -   i.) there no significant coke or coal (fuel) savings over that         of case (b);     -   ii.) the remaining discharged topgas provides less energy for         downstream uses than in case (b);     -   iii.) this case adds operational complexity of the CO2 removal         step;

iv.) there is a relatively small production increase from 8990 to 9010 T/day.

Case (d) illustrates a modified blast furnace operation wherein 002 is stripped and recycled topgas is injected at the rate of 73 Nm3/T to the mid-stack region of the furnace. Mid-stack injection of additional reducing gases is used in order to enhance the reducing potential in that region of the furnace. The results of this operational case (d) reveal no benefit over case (b) in terms of coke savings or topgas thermal energy production. There is a production increase from 8,990 to 9,407 T/day.

Case (e) illustrates a modified blast furnace wherein the quantity of mid-stack injected recycle gas was doubled in comparison to case (d). The results of case (e) are:

-   -   i.) reduced total fuel rate,     -   ii.) increased calorific value in the topgas,     -   iii.) a further enhancement in the total available thermal         energy produced for downstream power production,     -   iv.) additional enhanced productivity over case (d); and,     -   v.) an increase in equipment cost.

Case (f) illustrates a modified blast furnace wherein the mid-stack injection of stripped and recycled topgas is increased to the rate of 216 Nm3/T. The results of case (f) are:

-   -   i) increased productivity,     -   ii) lowered fuel requirement, and     -   iii) larger topgas energy available for export,     -   iv) thermal conditions in the bosh region (e.g., the region of         the blast furnace immediately in front of and around the tuyeres         of the Blast Furnace are unacceptably high (as indicated by the         RAFT of 2500° C.).

Case (g) illustrates a modified blast furnace wherein 100% O2 is used as the cold blast.

Case (g) employs CO2 removal from the topgas and recycle/reinjection of some of the CO2-stripped topgas to the bosh of the furnace and some of the CO2-stripped topgas to the mid-stack region of the furnace. The results of case (g) are:

-   -   i.) the highest illustrated productivity from the furnace of all         cases where the RAFT is within acceptable limits;     -   ii.) highest achievable topgas calorific value;     -   iii.) total fuel rate approaching to that of a conventional hot         blast operation (case (a)).     -   iv.) Increased equipment cost for CO2 stripping; recycling to         mid-stack injection; and recycling to tuyere injection.

Case (h) illustrates a modified blast furnace that uses 100% cold blast injection without recycling of CO2-stripped topgas to the tuyeres. This scheme cannot be employed because the RAFT is unacceptable.

Example B illustrates that case (b) has the affect of:

-   -   i.) Stove elimination through cold blast operation     -   ii.) production increase     -   iii.) coke rate reduction     -   iv.) sufficiently high calorific value topgas for economical         direct firing in a gas turbine in combined-cycle power         generation useful to combined cycle power generation.     -   v.) an increased total thermal energy made available for power         production     -   vi.) no mandated need for CO2-stripping and reinjection     -   vii.) no complicated modification or re-piping of the blast         Furnace for recycle reinjection to either the mid-stack or         tuyere region     -   viii.) while meeting the necessary thermal conditions (RAFT) in         the bosh of the furnace.

TABLE 2 Case (a) (b) (c) (d) (e) (f) (g) (h) Units Base Case Cold Blast Cold Blast Cold Blast Cold Blast Cold Blast Cold Blast Cold Blast Case comments Conventional Straight Some Recycle Recycle Recycle Pure O2 Pure O2 blast furnace cold blast topgas some more still more blast; blast; (with no cleaned topgas to topgas to topgas to Requires without TGR) of CO2 mid stack mid stack mid stack recycled topgas and injection injection injection topgas and recycle; recycled stack requires through injection massive tuyeres (both) stack injection; RAFT too high. Additional Attractive No fuel No small growing Complicated RAFT to comment Operation saved; advantage advantage advantage process high Need over (b) over (b) over (b): CO2 less fuel stripping; larger less topgas topgas energy energy for power BF Inputs Injected coal rate Kg/T 240 335 327 326 318 309 269 327 Blast Oxygen % 33.5 55.5 58.3 62.0 70.9 83.6 99.0 99.0 content Coke rate Kg/T 262 262 262 262 262 262 262 237 Moisture g/Nm3 18 9 9 9 9 9 0 0 Blast Temp. ° C. 1250 25 25 25 25 25 25 25 Req'd Blast Vol. Nm3/min 4385 3853 3637 3522 3143 2728 2162 2369 CO2 stripped and Nm3/T 0 0 46 0 0 0 175 0 recycled topgas through tuyeres Topgas injection Nm3/T 0 0 0 73 146 216 179 244 into stack Operational Results Topgas Calorific kJ/Nm3 4235 5744 5876 6030 6378 6787 7407 7214 Value Btu/scf 107.6 145.9 149.2 153.2 162.0 172.4 188.1 183.2 Raceway Adiabatic ° C. 2203 1996 1980 2129 2292 2500 2295 2602 Flame Temperature (RAFT) Topgas Quantity Nm3/T 1272 1229 1159 1142 1053 966 709 896 Avail. for power prod, (after stove heating and any re-injections) BF Productivity T/day 8608 8990 9010 9407 9862 10345 10253 10840 Thermal energy mill. MJ/hr 1.932 2.644 2.557 2.699 2.761 2.825 2.243 2.921 for power

Example C

Example C illustrates the affect of blast furnace process changes on the ability to produce power. A nominally-sized 2.3-million-ton-per-year Blast Furnace is operated according to the parameters shown in case (a) of Table 3—shown below (e.g., a coal injection at the rate of 150 Kg/T, a hot blast enriched with oxygen to the level of 26.6% by volume, and a corresponding coke rate of 339 Kg/T). Cases (b), (c), and (d) illustrate the affects which occur within this particular operation as the percentage of oxygen in the blast is increased from 26.6% to the progressively higher percentages of 33.3, 40, and 61%. These affects include:

-   -   i.) a corresponding increase in the amount of coal that can be         injected;     -   ii.) the temperature of the air blast is reduced;     -   iii.) the quantity of required air blast is reduced;     -   iv.) the amount of coke required in the charge is reduced to a         minimum “floor” level (which we have taken here to be 262 Kg/T),         after which point the coke rate can be held constant;     -   v.) more topgas thermal energy is produced;     -   vi.) a smaller portion of the total topgas is needed to heat the         stoves;     -   vii.) more of the topgas can be directed (dedicated) to         downstream power production;     -   viii.) there is diminished steam requirement to run turboblowers         or air blower supplying air to the blast stoves (e.g., as a         consequence of a reduction in air blast flowrate requirements),         and this additionally makes more steam produced by the energy         contained within the BF topgas energy available for power         production;     -   ix.) the ‘remaining MMbtu/hr of topgas available to power         generation increases from 619, to 924, to 1,236 to 1,843         MMbtu/hr as the Blast Furnace is operated at the corresponding         increased levels of oxygen enrichment and coal injection.

This Example illustrates an affect of a threefold increase in the amount of energy available for power production by raising the oxygen level in the air blast from 26.6% to 61% for this example Blast Furnace.

Referring now to Table 3, Table 3 illustrates the amount of “Net Power” (in kWe) that is produced for each of the Blast Furnace operational cases. For each of the Blast Furnace operating cases, the topgas is used in power production by one of two methods:

-   -   i.) Combust the topgas in a steam boiler and produce power via a         generator connected to a steam turbine (i.e., conventional         Rankine cycle power generation), or     -   ii.) Compress and combust the topgas in a Gas Turbine which         drives a generator, followed by taking the exhaust of the Gas         turbine to a Heat Recovery Steam Generator (HRSG) where this         steam then produces power through a properly-sized steam turbine         generator (i.e., combined cycle power generation).

Table 3 illustrates that the amount of electrical power that is generated raises dramatically as the Blast Furnace is additionally oxygen enriched, and a higher calorific value topgas is produced. Table 3 also illustrates the desirability of using combined cycle power production in order to increase the efficiency and raise the total amount of power than can be generated at each of the given blast furnace cases wherein the:

-   -   i.) Overall efficiency in the conversion of thermal energy into         kW of electrical energy remains fixed at 31.3% across the range         of produced topgas calorific values for the various BF operating         parameters.     -   ii.) In the case of Combined Cycle power production, the higher         calorific values of the topgas produced with higher oxygen         enriched BF operation yields efficiency advantages. This is         illustrated in the last row of numbers in Table 3 where the         overall net efficiency of conversion of topgas thermal energy         from the Blast Furnace rises from 38.1% to 43.7% as the oxygen         enrichment level in the air blast is increased from 26.6% to 61%         (along with other necessary corresponding changes in the BF         operating parameters).

While this example shows Blast Furnace operation and power generation efficiency at four specifically chosen points (or set of operating parameters), it is to be understood that a Blast Furnace can be operated at any suitable point along the disclosed range of oxygen concentration. For example, it might be desirable to operate at 52% oxygen if the projected quantity and calorific value of the topgas is most suitably matched to commercial availability of a specifically-sized gas turbine.

TABLE 3 Case Units (a) (b) (c) (d) BF Inputs Blast Oxygen % 26.6 33.3 40 61 content BF Fuel requirements Injected coal Kg/T 150 210 269 317 rate Coke rate Kg/T 339 301 262 262 total fuel rate Kg/T 489 510 531 579 Hot Blast Temp. ° C. 1150 975 800 204 Required blast rate Nm3/T 912 786.5 661 550 Operational Results BF Production Rate T/day 6301 6585 6868 6868 Top Gas Composition CO % 24.30 26.85 29.40 39.90 CO2 % 21.80 23.75 25.70 31.10 H2 % 4.60 6.45 8.30 10.10 N2 % 48.80 42.45 36.10 18.40 Ar % 0.50 0.50 0.50 0.50 total (dry) % 100.00 100.00 100.00 100.00 Topgas Calorific MJ/Nm3 3.66 4.21 4.77 6.33 Value (HHV) Btu/scf 92.9 107 121.2 160.7 Topgas Energy HHV 1273.6 1479.4 1682.8 2008.2 Produced MMbtu/hr calculations for amt. of topgas needed for stove heating Air blast lb/hr 682,076 614,686 538,848 448,360 O2 lb/hr 53,425 105,751 143,200 250,849 Air temp, inlet to ° F. 400 400 400 400 stoves O2 supply temp ° F. 60 60 60 60 Air temp, exit ° F. 2,102 1,787 1,472 400 stoves Stove heating duty, mmbtu/hr 343 280 210.6 23 (assumes 0.27 btu/ lb/F. sp. Heat) Stove HHV eff., % 85% 85% 85% 85% Topgas to stove HHV 403 329 247.7 0 heating, mmbtu/hr calculations for amt. of topgas needed to generate steam for turboblower Turboblower ICFM (at 148,963 134,245 117,683 97,920 ~60 F. avg ambient) % of design flow % 100%  90% 79% 66% Turboblower kWs 15,335 13,820 12,115 10,081 Turboblower ST lb/hr (at 153,355 138,203 121,152 100,807 steam ~10 lb/kw- hr) Steam duty (450#/ btu/lb 1,393 1,393 1,393 1,393 750 F.; 100 F. Cond, 60 F. makeup) Boiler HHV eff. % 85 85 85 85 Boiler fuel HHV 251 227 199 165 attributed mmbtu/hr to Turboblower Remaining topgas HHV 619 924 1,236 1,843 to power generation MMbtu/hr calculations for amount of electrical power production Rankine CC* Rankine CC* Rankine CC* Rankine CC* GT fuel compressor kWe 25,484 33,143 39,271 43,826 power kWe Air expander kWe 0 0 0 0 power Fuel High/Low 1.033 1.033 1.037 1.037 1.041 1.041 1.033 1.033 ratio LHV BTU/SCF AT 89 103 116 154 GT GT power kWe 62,432 92,786 123,718 185,925 GT power, lhv HR btu/kwh 9,600 9,600 9,600 9,600 ~GT exhaust heat kWthermal 116,859 174,485 233,488 348,010 portion to Rankine % 90% 90% 90% 90% cycle steam generation Input heat to kWthermal 175,607 105,173 260,987 157,037 347,991 210,139 522,964 313,209 Rankine cycle kWthermal Rankine cycle % 35% 35% 35% 35% 35% 35% 35% 35% gross lhv eff Rankine power kWe 61,463 36,811 91,345 54,963 121,797 73,549 183,037 109,623 production Aux power (~3% of kWe 1,844 1,104 2,740 1,649 3,654 2,206 5,491 3,289 Rankine power) Net Power kWe 59,619 72,654 88,605 112,957 118,143 155,789 177,546 248,434 Net HHV HR, 10,380 8,518 10,429 8,180 10,466 7,937 10,380 7,418 btu/kwh Net LHV HR, 10,053 8,249 10,053 7,886 10,053 7,624 10,053 7,185 btu/kwh Net LHV eff % 31.3 38.1 31.3 39.9 31.3 41.2 31.3 43.7 *Assumes ideal fit of size of gas turbine to amount of fuel gas

While the invention has been described in certain aspects, it is understood that the invention is not limited to such aspects and the invention covers various modifications and equivalents included within the scope of the appended claims. 

1. A method for producing iron comprising: introducing iron ore, coke and coal into a blast furnace, whereby the coal is gasified in the presence of steam and super-enriched air that are introduced into a blast furnace, recovering from the blast furnace a top gas and using the top gas to generate power; and, recovering hot metal from the blast furnace; wherein the super enriched air is introduced into the blast furnace at a temperature of less than about 1250 C and hot metal is produced at a reducing agent to iron ratio of greater than or equal to about 0.40 kg of carbon per kg of iron produced.
 2. The method of claim 1 wherein the air is enriched with oxygen from at least one member selected from the group consisting of an air separation unit, ion transport membrane and a VPSA.
 3. The method of claim 1 further comprising removing carbon dioxide from the top gas prior to said using.
 4. The method of claim 1 wherein the air blast is super-enriched with oxygen to a level above about 36% oxygen.
 5. The method of claim 1 wherein the usage of coke is less than about 300 kg per metric ton of hot metal and the coal rate is at least about 200 kg of coal per metric ton of hot metal.
 6. The method of claim 2 wherein the air separation unit comprises a cryogenic distillation air separation unit.
 7. A method for generating power comprising: providing at least a portion of top gas from an iron producing blast furnace wherein the top gas comprises carbon monoxide, carbon dioxide, hydrogen, and nitrogen each in concentrations such that the top gas has a calorific value, without supplemental fuel, that is sufficient to operate a gas turbine, compressing and supplying this top gas to the gas turbine, and; introducing an exhaust from the gas turbine into a heat recovery steam generator under conditions sufficient to operate a steam turbine.
 8. The method of claim 7 wherein the compressed gas supplied to the gas turbine is combined with nitrogen.
 9. The method of claim 8 wherein: i) the nitrogen is generated by an air separation unit (ASU) that supplies oxygen into the blast furnace, and/or ii) oxygen obtained from said ASU is used to combust a portion of the blast furnace top gas at a HRSG and/or iii) nitrogen from the ASU is supplied to the gas turbine.
 10. The method of claim 7 further comprising removing carbon dioxide from the top gas prior to introducing the gas into a gas turbine.
 11. The method of claim 10 further comprising converting at least a portion of the carbon monoxide into carbon dioxide prior to said removing carbon dioxide.
 12. A method for producing iron and gasifying coal comprising: introducing iron bearing materials, and coke into a blast furnace, introducing coal into the iron blast furnace, and; introducing air enriched in oxygen into the blast furnace, wherein the conditions within the blast furnace are sufficient to produce iron and convert at least a portion of the coal into a gas comprising carbon monoxide, carbon dioxide and hydrogen; removing a portion of the gas from the furnace; removing at least a portion of the carbon dioxide from the gas and supplying the gas to at least one of: i) a combined cycle power generation system and supplying steam generated by the combined cycle power generation system to the blast furnace, and ii) a water shift reactor to produce hydrogen; and, recovering iron from the iron blast furnace.
 13. The method of claim 12 wherein the oxygen used to enrich the air is supplied from an air separation unit.
 14. The method of claim 12 wherein the gas is supplied to a shift reactor wherein carbon monoxide and water are converted into carbon dioxide and hydrogen.
 15. The method of claim 13 wherein nitrogen generated by the air separation unit is supplied to at least one of the CO2 removing step, and supplying the gas to a combined cycle power generation system.
 16. The method of claim 13 where the furnace is supplied with a mixture comprising oxygen, steam and at least one of CO, CO2 and H2, and the gas is substantially free of nitrogen.
 17. The method of claim 7 wherein an exhaust exiting the steam turbine is substantially free of CO2.
 18. The method of claim 7 wherein at least a portion of the topgas is combusted in the presence of oxygen from an ASU in a burner of the heat recovery steam generator.
 19. An integrated system for producing iron and producing power comprising: an iron blast furnace and a top gas system for receiving the top gas from the iron blast furnace, a coal delivery system that supplies coal to the iron blast furnace, a carbon dioxide removal system that removes carbon dioxide from gas received from the top gas system, a combined cycle power generation system, a steam delivery system for supplying steam from the combined cycle power generation system to the iron blast furnace; and, an air separation unit and a delivering system for supplying oxygen from the unit to the blast furnace and nitrogen from the unit to the combined cycle power generation system.
 20. The system of claim 19 further comprising a water shift reactor that receives top gas from the top gas system and generates hydrogen.
 21. The method of claim 1 wherein the temperature is less than about 850 C.
 22. The method of claim 1 wherein the ratio is greater than or about 0.45 kg. 